The introduction of new television services such as DBS (direct broadcasting satellite) offers the opportunity of introducing new television standards. It is desirable that any new standard provide a means for backward-compatible extended definition, i.e. viewing a high definition picture on a standard monitor. Most of the new systems being contemplated provide an auxiliary data channel as part of the video format. Therefore this disclosure provides a means for utilizing the auxiliary data channel for picture quality enhancement.
In U.S. Pat. No. 4,323,916 "Data Rate Reduction for Digital Video Signals by Subsampling and Adaptive Reconstruction" (R. A. Dischert and G. A. Reitmeier) a means was disclosed to enhance the resolution of a transmitted digital video signal by including "steering bits" in the data stream that indicate to a decoder which output of the outputs of several postfilters should be applied to reconstruct a deleted sample in the optimal way. The same concept can be applied to extending the resolution of an analog transmitted DBS signal by sampling it and computing intermediate samples in accordance with instructions in steering bits transmitted with the signal. In general, the data rate of the auxiliary channel is not high enough to support the number of bits required to control the filtering on a pixel-by-pixel basis.
In the previously mentioned patent, the encoder produces reconstruction filter control or steering bits according to which filter produces the "best" estimate, but the control bits may change to indicate a change in the reconstruction filter when the difference between the current "best" estimate and the previous "best" estimate may be as little as one quantization level and as a result, the control bits occur in a very random fashion, since they respond to noise and very small changes in picture content. This invention provides for modifications to the encoder of the aforementioned patent, that modifyies the generation of bits in order to greatly reduce the randomness of the filter control bits, which allows for a great amount of data reduction by further encoding the control bits.